It is well known that the real world, a 3D world, provides people two position-shifted images through their eyes, which images form an optical parallax required for 3D viewing after entering the eyes, and then generate a 3D perception under fusion reflection of optic nerve center and visuopsychic reaction.
People desire more and more for the technique of displaying more real images as development of high-definition TV (HDTV) technique in recent years. The left and right position-shifted images are provided to the left and right eyes respectively through a display screen based on this 3D imaging theory, so as to generate a 3D perception.
It has already developed 3D display techniques such as 3D glasses and HMD (Head Mounted Display). However, the aforementioned 3D display techniques such as wearing 3D glasses or HMD may cause discomfort to viewer's eyes, and decrease the comfort level of watching. Therefore, an auto stereoscopic display technique, i.e. naked eye visual auto-stereoscopic image display technique becomes a focus for display technique researches.